In silico Functional and Structural Annotation of the qseB/qseC-encoded Quorum Sensing System in a Clinical Isolate of Klebsiella aerogenes

Quorum sensing (QS) is a microbial communication mechanism that can modulate the expression of specific genes related to virulence, biofilm formation, antimicrobial resistance, enzyme production, adaptability to adverse conditions, among others. Various QS systems have been described, including the QseB/QseC system. In Klebsiella aerogenes, a nosocomial pathogen, this system remains poorly understood. This study aimed to identify the qseB and qseC genes in the genome of a clinical isolate of K. aerogenes, as well as to characterize the functions and structures of the QseB and QseC proteins. We utilized a suite of bioinformatics tools to assess the physicochemical and structural properties of these proteins, predict signal peptide presence, secretion pathways, subcellular localization, antigenic sites, and functional roles. Additionally, we modeled the three-dimensional structures and determined the active sites of QseB and QseC. Our results confirm the presence of qseB and qseC genes in the K. aerogenes. In silico analyses revealed that both proteins are stable, hydrophilic, and exhibit similar instability indices. Neither protein contains signal peptides for secretion; QseB is localized in the cytoplasm, while QseC is situated in the cellular membrane. Both proteins possess antigenic determinants. Functionally, QseB acts as a DNA-binding response regulator, whereas QseC functions as a histidine kinase. Structural models validated exhibit high-quality predictions for both proteins. Active site analysis pinpointed crucial amino acid residues involved in the biochemical activities of both proteins. These data show that the isolate has a complete QseB/QseC system that recognizes AI-3 and catecholamines and may modulate genes essential to pathogenicity.

Keywords:
bioinformatics analyses; bacterial communication mechanisms; QseB and QseC proteins; function prediction; structural modeling.

Klebsiella aerogenes contains only a single copy of the qseB and qseC genes.

QseB is a cytoplasmic protein with DNA-binding domains.

QseC is a membrane-localized protein with histidine kinase functionality.

Both proteins are not secreted, lack signal peptides, and are stable.